On my first build, I sealed it to the top of the floor. That's an example of not thinking the build through from the get-go. It works but only because the hatch is thick enough for four seal strips––and the fact that the top of the galley floor is epoxied.

On the last two builds, the hatch seals to the edge of the floor. It's a much better way of sealing it up.

Make sure you build it so there is enough gap for the crushed seal to fit.